Commit ae21ee65e8bc228416bbcc8a1da01c56a847a60c "PCI: acs p2p upsteram
forwarding enabling" doesn't actually enable ACS.
Add a function to pci core to allow an IOMMU to request that ACS
be enabled. The existing mechanism of using iommu_found() in the pci
core to know when ACS should be enabled doesn't actually work due to
initialization order; iommu has only been detected not initialized.
Have Intel and AMD IOMMUs request ACS, and Xen does as well during early
init of dom0.
Cc: Allen Kay <allen.m.kay@xxxxxxxxx>
Cc: David Woodhouse <dwmw2@xxxxxxxxxxxxx>
Cc: Jeremy Fitzhardinge <jeremy@xxxxxxxx>
Cc: Joerg Roedel <joerg.roedel@xxxxxxx>
Signed-off-by: Chris Wright <chrisw@xxxxxxxxxxxx>
---
Applies against the linux-next branch of Jesse's pci tree.
arch/x86/kernel/amd_iommu_init.c | 2 ++
arch/x86/xen/enlighten.c | 5 +++++
drivers/pci/dmar.c | 5 ++++-
drivers/pci/pci.c | 13 +++++++++++++
drivers/pci/probe.c | 5 +----
include/linux/pci.h | 2 ++
6 files changed, 27 insertions(+), 5 deletions(-)
diff --git a/arch/x86/kernel/amd_iommu_init.c b/arch/x86/kernel/amd_iommu_init.c
index b4b61d4..e60530a 100644
--- a/arch/x86/kernel/amd_iommu_init.c
+++ b/arch/x86/kernel/amd_iommu_init.c
@@ -1330,6 +1330,8 @@ void __init amd_iommu_detect(void)
gart_iommu_aperture_disabled = 1;
gart_iommu_aperture = 0;
#endif
+ /* Make sure ACS will be enabled */
+ pci_request_acs();
}
}
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 5bccd70..e2511bc 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -27,6 +27,7 @@
#include <linux/page-flags.h>
#include <linux/highmem.h>
#include <linux/console.h>
+#include <linux/pci.h>
#include <xen/xen.h>
#include <xen/interface/xen.h>
@@ -1170,7 +1171,11 @@ asmlinkage void __init xen_start_kernel(void)
add_preferred_console("xenboot", 0, NULL);
add_preferred_console("tty", 0, NULL);
add_preferred_console("hvc", 0, NULL);
+ } else {
+ /* Make sure ACS will be enabled */
+ pci_request_acs();
}
+
xen_raw_console_write("about to get started...\n");
diff --git a/drivers/pci/dmar.c b/drivers/pci/dmar.c
index e01ca4d..0e98f6b 100644
--- a/drivers/pci/dmar.c
+++ b/drivers/pci/dmar.c
@@ -614,8 +614,11 @@ void __init detect_intel_iommu(void)
#endif
#ifdef CONFIG_DMAR
if (ret && !no_iommu && !iommu_detected && !swiotlb &&
- !dmar_disabled)
+ !dmar_disabled) {
iommu_detected = 1;
+ /* Make sure ACS will be enabled */
+ pci_request_acs();
+ }
#endif
}
early_acpi_os_unmap_memory(dmar_tbl, dmar_tbl_size);
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 453d6ba..fc8fa3f 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -1550,6 +1550,16 @@ void pci_enable_ari(struct pci_dev *dev)
bridge->ari_enabled = 1;
}
+static int pci_acs_enable;
+
+/**
+ * pci_request_acs - ask for ACS to be enabled if supported
+ */
+void pci_request_acs(void)
+{
+ pci_acs_enable = 1;
+}
+
/**
* pci_enable_acs - enable ACS if hardware support it
* @dev: the PCI device
@@ -1560,6 +1570,9 @@ void pci_enable_acs(struct pci_dev *dev)
u16 cap;
u16 ctrl;
+ if (!pci_acs_enable)
+ return;
+
if (!pci_is_pcie(dev))
return;
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 2fdffc0..98ffb2d 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -10,9 +10,7 @@
#include <linux/module.h>
#include <linux/cpumask.h>
#include <linux/pci-aspm.h>
-#include <linux/iommu.h>
#include <acpi/acpi_hest.h>
-#include <xen/xen.h>
#include "pci.h"
#define CARDBUS_LATENCY_TIMER 176 /* secondary latency timer */
@@ -1029,8 +1027,7 @@ static void pci_init_capabilities(struct pci_dev *dev)
pci_iov_init(dev);
/* Enable ACS P2P upstream forwarding */
- if (iommu_found() || xen_initial_domain())
- pci_enable_acs(dev);
+ pci_enable_acs(dev);
}
void pci_device_add(struct pci_dev *dev, struct pci_bus *bus)
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 2891c3d..04771b9 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1328,5 +1328,7 @@ static inline bool pci_is_pcie(struct pci_dev *dev)
return !!pci_pcie_cap(dev);
}
+void pci_request_acs(void);
+
#endif /* __KERNEL__ */
#endif /* LINUX_PCI_H */
--
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